The invention relates generally to impact machinery that undergoes heavy vibrations under operation. More specifically, the invention relates to a system and method for monitoring rappers in an electrostatic precipitator.
Many industrial operations produce exhaust gases that contain dust, fly ash (unburned constituents from burning), fumes (fine elemental particles such as cadmium, sulfur and lead) and mist (such as coal tar), which are undesirable for the environment. One widely used method of removing such contaminants from a gas stream is to use an electrostatic precipitator (ESP).
In one example, electrostatic precipitators are composed of metallic plates subjected to a potential difference in order to exploit the corona activity and capture the electrostatically charged dust of the smoke exiting from the smokestack of a factory. The plates are bumped at regular intervals for dust removal by using rappers, and the dust is then collected at the bottom of the electrostatic precipitators. Rappers include machinery that creates an impact as part of its normal operation and needs to be carefully monitored for performance, efficiency, and safety reasons. For example, electromagnetic rappers are used to knock dust off of electrostatic precipitator (ESP) plates by lifting a heavy slug using an energized electric coil and then dropping the slug onto the ESP plate at periodic intervals. The resulting impact is several hundred times normal earth gravity. A precipitator may have several hundred rappers, and it is not practical to monitor all of them manually.
Conventional shock and vibration instrumentation includes accelerometers and signal analyzers. Employing such equipment is expensive and cumbersome. For example, to fit the monitoring equipment within a small space so as not to interfere with normal operation involves expensive modifications to available equipment. Additionally, supplying power and data lines to each unit is a challenge with respect to logistics and installation. Furthermore, conventional sensors are often not sufficiently rugged to withstand the temperature, pressure, electromagnetic interference, or combinations thereof in the harsh environments of the type which are experienced by ESPs for extended periods of time.
It is increasingly becoming important to have better operating and maintenance procedures for electrostatic precipitators and other impact machinery and apparatuses.